Protector for gauges and the like



Oct. 17, 1967 w. RAST PROTECTOR FOR GAUGES AND THE LIKE Filed Aug. 11,1964 United States Patent 3,347,272 PROTECTOR FOR GAUGES AND THE LIKEWlodzimierz Rast, Flinders Park, South Australia, Australia, assignor toRast Industries Limited, Flinders Park, South Australia, Australia FiledAug. 11, 1964, Ser. No. 388,805 3 Claims. (Cl. 138-30) This inventionrelates to a protector for gauges and the like and in particular itrelates to a device which will limit the sudden fluctuation of gaugescommonly found with pressure gauges and the like where rapid pressurevariations occur.

It will be known that gauges which measure hydraulic or pneumaticpressure will be damaged when suddenly subjected to large variations inpressure, and also that very rapid deterioration of the mechanism of agauge can occur where small relatively high frequency variations occurwhich cause chatter in the gauge and consequently wearing out of themechanism within a very short time.

Heretofore there has been no effective means of protecting gaugesagainst this type of damage or wear and it is therefore the object ofthis invention to provide a protector which will be efi'ective under theconditions met with and which will damp out sudden changes which couldcause rapid fluctuations of the gauges.

It is a further object of this invention to so construct the meanswhereby these'fluctuations will be avoided that there is no danger ofblockage of the means which would render the gauge ineffective.

The object of the invention is achieved by providing a limiter betweenthe supply line and the gauge which restricts the flow of fluid to thegauge and thus prevents sudden changes on the gauge itself, the purposeof the limiter being to restrict the flow to such an extent that thegauge read an average rather than being influenced by suddenfluctuations.

To ensure that the restrictor does not become blocked by sediments orparticles carried by the oil or other medium when reading a pressure,the protector according to this invention is a sealed unit utilising itsown pressure fluid and thereby avoiding any danger of blockage of therestrictor or of impurities entering the gauge.

An advantage resulting from the invention is that by use of the devicethere is no danger of a sudden outflow of a large quantity of a pressurefluid from the gauge should the gauge be broken or blown out.

According to this invention the protector comprises a member adapted tobe inserted between the pressure line and the gauge which has in it arestrictor whereby the flow is limited and a bag which is adapted toisolate fluid so that the fluid which operates through the restrictorand into the valve can not mingle with the pressure fluid which actuatesthe gauge.

To enable the invention to be fully understood an embodiment of samewill now be described with reference to the accompanying drawingdesignated FIG. 1 which is a central section of the gauge protector andwhich shows a preferred form although the invention need not necessarilybe limited to this particular form, being defined in the claims appendedhereunto.

A hollow body 1 has its two ends closed by means of plugs 2 and 3, theplug 2 having in it a threaded aperture 4 into which a gauge which is tobe protected may be screwed, the plug 3 having on it a threaded boss 5to which the pressure line is adapted to be attached whereby the plugs 2and 3 act as connectors respectively for a gauge and a pressure line.The plug 2 has a tapped axially outer end in its bore and a reduceddiameter axially inner end.

Both plugs are locked in position in the hollow body 1 after beingscrewed thereinto, the body being provided 3,347,272 Patented Oct. 17,1967 with threads 6 and 7 for this purpose, and the plugs 2 and 3 beingthen locked in position by means of retaining screws 8 and 9 which fitinto threaded apertures formed on the joining plane between therespective plugs 2 and 3 and the hollow body 1.

The injunction between the plug 3 and the body 1 is sealed by means ofan O ring 10 carried in a recess 11 in the body 1 and bearing against a.cylindrical face 12 on the plug 3.

The joint between the plug 2 and the hollow 1 is similarly sealed by anO ring 14 disposed in a groove 15 in the hollow body 1 and bearingagainst a cylindrical surface 16 on the plug 2.

The O ring 14 forms the lip of a resilient bag 18 which depends into thehollow body 1 between the two plugs 2 and 3, and this bag 18 is adaptedto contain a fluid 19 which is the fluid which operates the gauge, theinside of the bag 18 being in communication with the threaded socket 4to which the gauge fits through a restrictor 20 which is of a porousnature so that the fluid 19 can pass through it but is suflicientlyrestricted in its flow so that a sudden flow cannot take place whichwould be capable of damaging the valve, this restrictor being held inplace by a hollow threaded screw 21 engaging in a threaded aperture 22communicating with the aperture 4 in the plug 2.

Instead of using a porous restrictor 2a a small aperture or a series ofsmall apertures could be used or a sintered metal or the like could beselected, the purpose of this restrictor being as said to limit the rateof flow of the fluid 19 through it by means of which the gauge isoperated.

The bag or membrane may be formed of polythene or any other suitableflexible material which is adapted to contain an amount of fluidsufllcient when pressure is exerted on the bag to flow into the gauge tooperate same, the fluid of course having to pass through the restrictor20 on its way from the bag to the gauge.

It will be realised therefore that the pressure line fluid does not haveaccess to the gauge but only to the inside of the hollow body 1 where itacts on the outside of the bag 18 to compress the bag 18 and thus forcethe fluid from the bag through the restrictor 20 into the gauge, thegauge itself being thus completely sealed oil from the liquid in thepressure line and thus not subject to be blocked by impurities whichcould be contained in this liquid.

It will be realised of course that the bag can be varied in its form andit could be in the nature of a hollow or diaphragm provided suificientmovement is given to allow fluid isolated by the bag to actuate thegauge from pressure exerted on the bag by the liquid in the pressureline.

From the foregoing it will be seen that the objects of the invention areattained because of the presence of a restrictor 20 either in the natureof a small aperture or apertures or of a body of fibre glass or similarpermeable material which provides a number of interstices or smallapertures through which fluid can collectively flow but because of thenumber used and the resistance offered because of their small size, theflow is restricted so that a considerable pressure ditferential can beachieved across the restrictor, this pressure difference then allowing atime delay to be introduced in the transferring of the pressure from oneside to the other so that a sudden building up of pressure will notreach the gauge in that form but will be of a more gradual nature, andsimilarly a sudden tall in pressure will again be transmitted as aslower change through the restrictor.

In this way it is possible to damp out sudden large fluctuations whichwould damage the needle and mechanism of the gauge, and similarly highfrequency pressure of the gauge can also be cut out, the invention thusachieving its object of providing a protector for the gauge which willgive better reading of the gauge and at the same time will avoid damageto the gauge.

Because of the use of an isolating bag 18 between the actual pressurefluid being measured and an isolated fluid which operates the valveitself, it will be realized that the restrictor will not be subject toblockage by impurities or the like as the liquid which is isolated bythe bag can be carefully selected to avoid any blockage or contaminationof the restrictor.

Similarly the advantage is achieved that should the gauge itself blowout or be damaged there will not be a continued rush of the pressurefluid from the line because the bag 18 will simply be forced against therestrictor 20 or the opening to it and will then shut this off.

By unscrewing the plug 3 from the body 1 it is possible to clean thehollow within the body without losing the fluid from within the bag 13,thus making the device suitable for supporting a gauge in foodprocessing or the like where periodic cleaning or sterilization must beeffected.

What I claim is:

1. A protector for gauges comprising an elongate hollow body, a firsthollow connector removably held on one end of said hollow body toconnect the hollow body to a pressure line, a second hollow connectorremovably held on the other end of said hollow body to connect thehollow body to a gauge, a sealing member between the first connector andthe body, a sealing member between the second connector and the body, aresilient bag having one end open and the other end closed fitting intoand substantially filling the hollow of the said body, said bag havingits open end communicating with the second hollow connector but sealedfrom the first hollow connector, a porous restrictor having a pluralityof apertures therein positioned in the hollow of the second connector,between the second hollow connector and the open end of said bag, and ahollow threaded screw engaging in a threaded portion of the hollow ofthe second connector and securing said restrictor in the hollow of thesecond connector.

2. A protector for gauges comprising a hollow body, a first hollowconnector removably secured to one end of said hollow body to connectthe hollow body to a pressure line, a second hollow connector removablysecured to the other end of said hollow body to connect the hollow bodyto a gauge, a sealing member between the first connector and the body, aresilient bag having one end open connecting to said second connectorand the other end closed fitting into and substantially filling thehollow of the said body and integral with a sealing member disposedbetween the second connector and the body, a restrictor positioned inthe hollow of the second connector, said restrictor having a pluralityof small interstices which restrict the flow of a fluid therethrough, aliquid received in said bag in suflicient quantity to flow through saidrestrictor, through said second hollow connector to a gauge to operatethe same, and hollow threaded screw means engaging a reduced diameterthreaded portion of the hollow of the second connector to removably butfirmly hold the restrictor in the hollow of the second connector.

3. A protector for gauges comprising an elongate hollow body, a firsthollow connector removably held on one end of said hollow body toconnect the hollow body to a pressure line, a second hollow connectorremovably engaging the other end of said hollow body and being receivedtherein, said second hollow connector having a tapped bore section atits outer end to connect the hollow body to a gauge, a sealing memberbetween the first connector and the body, a resilient bag having one endopen and the other end closed received in and substantially filling thehollow of the said body and integral with a sealing member disposedbetween the second connector and the body, said second hollow connectorhaving a reduced diameter bore section at its inner end, a restrictorpositioned in the reduced diameter bore section of the second connector,said restrictor having a lurality of small interstices which restrictthe flow of a fluid therethrough, said bag being of a size as to receivesufficient liquid to flow through said restrictor, the bore of saidsecond hollow body and to a gauge connected thereto to operate suchgauge, and hollow threaded screw means engaging a threaded portion ofthe reduced diameter bore section of the second connector to removablybut firmly hold the restrictor in the hollow of the second connector.

References Cited UNITED STATES PATENTS 1,832,380 11/1931 Goldman 73-392X 2,317,073 4/1943 Martin 73395 X 2,550,892 5/1951 Weber et al. 138-30FOREIGN PATENTS 817,043 10/1951 Germany.

LAVERNE D. GEIGER, Primary Examiner,

C. L. HOUCK, Assistant Examiner,

1. A PROTECTOR FOR GAUGES COMPRISING AN ELONGATE HOLLOW BODY, A FIRSTHOLLOW CONNECTOR REMOVABLY HELD ON ONE END OF SAID HOLLOW BODY TOCONNECTED THE HOLLOW BODY TO A PRESSURE LINE, A SECOND HOLLOW CONNECTORREMOVABLY HELD ON THE OTHER END OF SAID HOLLOW BODY TO CONNECT THEHOLLOW BODY TO A GAUGE, A SEALING MEMBER BETWEEN THE FIRST CONNECTOR ANDTHE BODY, A SEALING MEMBER BETWEEN THE SECOND CONNECTOR AND THE BODY, ARESILIENT BAG HAVING ONE END OPEN AND THE OTHER END CLOSED FITTING INTOAND SUBSTANTIALLY FILLING THE HOLLOW OF THE SAID BODY, SAID BAG HAVINGITS OPEN END COMMUNICATING WITH THE SECOND HOLLOW CONNECTOR BUT SEALEDFROM THE FIRST HOLLOW CONNECTOR, A POROUS RESTRICTOR HAVING A PLURALITYOF APERTURES THEREIN POSITIONED IN THE HOLLOW OF THE SECOND CONNECTOR,BETWEEN THE SECOND HOLLOW CONNECTOR AND THE OPEN END OF SAID BAG, AND AHOLLOW THREADED SCREW ENGAGING IN A THREADED PORTION OF THE HOLLOW OFTHE SECOND CONNECTOR AND SECURING SAID RESTRICTOR IN THE HOLLOW OF THESECOND CONNECTOR.